Ferroelectric random access memories (FeRAMs) are nonvolatile memories including ferroelectric capacitors having a ferroelectric film. FeRAMs are advantageous in that high-speed operation can be realized, electric power consumption is low, and they have excellent durability in writing and reading. An example of the ferroelectric film used for the ferroelectric capacitors of FeRAMs is a film of lead zirconate titanate (PbZr1−x-TixO3, PZT)
Such a ferroelectric film, e.g., a PZT film, has a property that it is easily degraded by hydrogen and moisture. Hydrogen and moisture enter from the outside or they are generated during a process of forming the FeRAMs. Therefore, normal FeRAMs have a structure in which the ferroelectric capacitor portions are covered with an aluminum oxide (AlO) film or the like so as to prevent hydrogen and moisture from entering the ferroelectric capacitors (for example, see U.S. Pat. No. 7,115,994 and US 2006-0281300A).